地磁偏角实时自动修正技术在油田定向钻井中的应用

在油田定向钻井的磁导向定位系统中，地磁偏角校正是一个不可缺少的基本要素，同时在磁偏角校正值精度直接影响定向井的导向定位精度。因此，作者提出了提高地磁偏角校正值精度的方法，并试图将地磁偏角实时自动修正技术引入我国油田定向钻井领域。     

磁偏角的周期性变化

利用磁偏角预报地震,必须考虑磁偏角正常的周期性变化,才能正确判定异常。根据我们小组四年多来的磁偏角自动记录资料,谈谈对磁偏角正常周期性变化的认识。 磁偏角的年变化 磁偏角的年变化有:1、定向漂移,主要是地磁极移动引起的,观测数据的均值呈现出缓     

磁偏角磁变仪的定向

分析了影响磁偏角磁变仪定向质量的原因，指出应重视阻尼器影响，提出磁偏角磁变仪以在实际工作环境中定向最佳，用扭头带动镜面法定向实用性强，无须做任何改正。     

分量核旋仪偏置电流对磁偏角测量的影响分析

从理论上定量地分析了FHD-1型分量核旋仪的偏置电流对磁偏角观测值的影响,结果表明偏置电流的漂移对磁偏角观测值的影响随偏置电流的漂移量的增大而增大、也随磁偏角观测值的增大而增大,该结果对指导台站提高该仪器磁偏角观测值的精度有一定意义。     

磁偏角变化对垂直分量磁变仪记录影响的实验

实验证实了磁偏角变化对垂直分量磁变仪记录有影响。对于磁南北向布局中的垂直分量磁变仪，Ｚ磁针偏离定向位置θ０＝０越远，磁偏角变化对垂直分量磁变仪记录的影响越大。认为应重视垂直分量磁变仪遥定向工作并有必要提高垂直分量磁变仪磁针稳定性。     

土地磁磁偏角“极小值”与强震的对应关系

1969年渤海地震前兆总结会议上,曾有专文讨论磁偏角与渤海大震的关系。以后各地专业台站在运用磁偏角予报地震方面积累了不少经验,随着陶瓷偏角仪的推广,各地群测点的磁偏角观测工作蓬勃开展起来。     

溧阳6.0级地震前的磁偏角异常

本文根据溧阳六级地震后对近二百台磁偏角资料调查结果,提出对磁偏角资料质量的评定办法和选择标准,指出绝大多数(约98％以上)测点都受到环境条件、设备条件等严重干扰。通过溧阳六级震前磁偏角异常的分析,认为可分辨的异常仅限于离震中100公里范围内,异常期不到两个月。本文认为,必须对磁偏角观测工作进行全面的整顿和改造,若能真正使资料质量得到保证,磁偏角还是可望在地震的短期预报中发挥作用的。     

机场跑道磁偏角测量

磁偏角是机场建设中一个重要的测量数据,《民用机场勘测规范》（2008）要求磁偏角的测量精度优于0.1°,而目前教科书和有关测量规范并未给出相关方案。本文描述了某机场磁偏角施测的技术过程：根据当地磁偏角的日变特征,选取每日6：00—8：30及17：30—19：30进行观测,测距400 m;连续2天共测得29个观测数据,数据标准差为1.93',与机场跑道外侧草坪内2个观测点的磁偏角相差3.93',均小于0.1°,说明本次观测数据稳定可信,观测成果满足技术指标。     

磁通门经纬仪分量测量法在机场磁偏角测量中的应用

探讨利用磁通门经纬仪（DI仪）测量机场磁偏角的新方法——分量测量法,即利用DI仪测量的地磁场水平分量（X、Y）计算磁偏角。对影响磁偏角测量精度的主要因素进行分析,详细阐述DI仪测量地磁场水平分量及磁偏角的计算过程。实践表明,采用分量法对机场磁偏角进行观测和计算是合理的。这种测量方法与常规的近零法所得测量结果相吻合,其测量精度满足相关测量规范的要求。而且,由于分量法在测量地磁偏角的过程中无需追踪水平磁场的零位,因而操作更简便、作业效率更高,更适合机场、码头等野外测量场合。     

磁偏角磁变仪的定向实验

对磁偏角磁变仪进行了定向实验,实验表明磁偏角磁变仪精确定向以在实际工作的环境中进行最佳。磁偏角磁变仪磁针保持定向能力强,垂直分量磁变仪等对该仪器的定向影响可以忽略,不必进行定向改正。     

现代风成沉积物磁化率各向异性与风向关系的研究

通过对风洞及室内模拟定向风条件下的风成沉积物磁化率各向异性与风向之间关系的研究,发现风成沉积物磁化率各向异性的长轴方向的偏角不仅与风向有关,而且与粉尘沉积量有关。风成沉积物磁化率各向异性的长轴方向的偏角在α95（α95≤20°）的区间范围内与粉尘沉积量大的风向一致．在干旱、半干旱区,现代风成沉积物（沙丘、黄土的表层土）的磁化率各向异性的长轴方向的偏角在此范围区间内与常年盛行风向一致,尤其与沉积物沉降时的盛行风向一致．     

Magnetic declination measurements over European Russia and Siberia in the 18th century

The paper presents the history of measurements of the geomagnetic field parameters over the territory of Russia in the 18th century derived from archival and literature sources. Topographical mapping of the European territory and neighboring seas of the Russian Empire from the late 17th to the mid 18th century during which magnetic measurements were made was of great importance for determining magnetic declination. The magnetic declination in Siberia and its neighboring seas was measured for the first time during the first expedition of V. Bering in 1728 and then during his second expedition (the Great Northern Expedition) in 1733–1742. Magnetic measurements were carried out along the northern coast of Siberia and in the Bering Sea. The academic group of the expedition performed magnetic declination measurements over southern regions of Siberia (Krasnoyarsk, Irkutsk, Nerchinsk, Yakutsk, etc.) in 1735 and 1736. During the second half of the 18th century, Russian expeditions determined geographical coordinates of the cities of European Russia and carried out magnetic declination measurements for them. During these expeditions Inokhodtsev paid attention to the anomalous magnetic declination in the Kursk region. In his opinion, the anomaly could have been caused by the presence of iron ore.     

地震震中和地磁偏角的空间分布

对1900～2002年全球记录到的震级M≥4．0地震震中,利用IGRF（国际地球参考场）国际参考模型确定地磁场的特征。研究了主要地震活动带的地理学和内源引发的基本地磁场几何学之间的关系,查明了不同构造类型的地震活动带全球分布与地磁偏角或地磁场东-西向分量分布之间的构造对应。     

兰州地磁台GPS差分方位角的测量

为了适应高采样率、高分辨率、高精度的新型地磁仪器对磁偏角和磁倾角观测的需要,应用GPS测定了改造后的兰州地磁台的7个观测墩（一个临时观测墩）至2个方位标志的方位角,共取得了13个方位角参数,使兰州地磁台在地磁偏角测量或仪器验收比测中可供6套仪器同时观测,并可做到全天候观测。     

Effects of neutral wind on the electron temperature at a height of 600 km in the low latitude region

Electron temperature observed by the Hinotori satellite with the low inclination at the height of \sim600 km was studied in terms of local time, season, latitude, magnetic declination and solar flux intensity during a 16-month period from 1981 to 1982. The electron temperatures show steep rise in the early morning (well known as morning overshoot), decrease after that and again increase at \sim18 hours (hereafter named as evening overshoot). Generally the morning overshoot becomes more enhanced in the winter hemisphere and for higher solar fluxes. The evening overshoot becomes more pronounced in the mid-latitude in all seasons and more enhanced in the winter hemisphere in the same way as the morning overshoot. A difference is seen between 210°-285° and 285°-360° longitudes where magnetic declination is different. The longitudinal dependence of electron temperature indicates that the neutral wind also contributes to the thermal structure in the low latitude ionosphere.     

Estimating the Influence of Geomagnetic Disturbances on the Trajectory of the Directional Drilling of Deep Wells in the Arctic Region

At high latitudes, sporadic geomagnetic disturbances associated with geomagnetic storms introduce significant uncertainty in measurements by borehole inclinometers during the directional drilling of deep wells. Variations in the magnetic declination may lead to significant deviations of the actual coordinates of the borehole from the prescribed trajectory. Using the methods for calculating the profile of the actual borehole, we conducted model estimates of the influence of sporadic disturbances in the magnetic declination observed during the magnetic storm of October 28–31, 2003 on the displacement azimuth and intensity of borehole bending at the given locations at the sites of two high-latitude magnetic observatories. It is shown that, unless filtered based on the data of parallel observatory measurements, the geomagnetic disturbances can lead to unacceptably large errors in the borehole inclinometer measurements and cause a borehole deflection exceeding the admissible values.     

地磁方位标志的稳定性与磁偏角观测精度的研究

地磁台是产出连续完整、准确可靠的地球磁场变化数据的场所。而对某测点地球磁场的描述是以磁偏角D、磁倾角I、总强度F、水平强度H、北向强度X、西向强度Y、垂直强度Z等七要素为依据。其中只需直接测定3个独立量,如D、H、Z或DI、、F等组合,则其它量可通过数学关系求得。特别是,磁偏角D在观测中非常重要。本文对静海地磁台改造后连续7年(2002~2008年)的观测记录资料,进行了认真整理和细致研究,研究了标志的漂移对观测值D的影响,说明了观测标志稳定的重要性。